How Nutrient Needs Change for Exerciser

It's outdoor weather, time for exercise procrastinators to get rid of their excuses and for winter joggers to swap their sweats for shorts.

It's also time for a brief review of sports nutrition.

According to Joanne Slavin, assistant professor of nutrition at the University of Minnesota, most Americans, whether they're athletes or not, could stand to make some changes in their diet.

Athletes should be aware of how their nutrient needs change during exercise. In a publication of the University of Minnesota Agricultural Extension Service, Slavin gives her perspective on some common sports-nutrition questions. Here are some excerpts:

Question: Shouldn't athletes consume more protein?

Answer: No. Early nutrition experiments found that protein needs are the same whether you're climbing a mountain or watching someone else climb one. Besides, most Americans consume about twice as much protein as they need. Extra protein is quickly converted to fat.

Q: If an athlete is involved in strenuous exercise and needs to consume more calories, where should these calories come from?

A: Carbohydrates. The immediate source of energy for exercising muscle comes from glycogen, a carbohydrate storage compound found in the muscle. Glycogen is very limited. With strenuous, sustained activity, it is quickly used up, forcing the muscles to use fat stores. However, muscles prefer to use glycogen. Eating a high-carbohydrate diet (preferably in the form of whole-wheat grains and fruits and vegetables) will increase muscle glycogen even further.

Q: Are commercial sports drinks preferable to water during and after exercise?

A: Not usually. Sweat is mostly water, so water is the most important substance to replace. And salt tablets will actually draw more water into the stomach from other body tissues and can make the existing dehydration problem worse.

Q: Should rehydrating solutions contain sugar?

A: Sugars slow the rate at which fluids leave the stomach. Most research suggests that sugar content of sports drinks should not exceed 2 to 2.5 grams per 100 milliliters, or about 1 teaspoon of sugar in 1 cup of water. Most sports drinks contain two to three times the recommended amount of sugar and should be diluted at least 50%.

Q: What's a good pregame meal?

A: If an athlete has been consuming a high-carbohydrate diet during the week before competition, glycogen stores should be high. So what an athlete eats the day of competition will not affect muscle glycogen. Most authorities recommend eating three to four hours before competition so the stomach will have time to empty. High-protein, high-fat meats are not digested as quickly as carbohydrates and should be limited in the pregame meal.

For her own meals, Slavin sticks with naturally high-carbohydrate pasta dishes, topped with fresh vegetables.

Here's an adaptation of a favorite meal of Slavin's. Make sure you have butter or margarine, flour and pepper on your shelves before you jog to the store.

FETTUCCINE WITH

ASPARAGUS, GRUYERE

CHEESE SAUCE

2 1/2 cups asparagus, cut in 1-inch pieces

1 pound fettuccine, cooked

2 tablespoons butter or margarine

1 1/2 tablespoons flour

1 cup low-fat milk

1 cup grated Gruyere cheese

Freshly ground black pepper

Place asparagus in steamer. Steam until barely tender-crisp, about 10 minutes.

Melt butter in saucepan over low heat. Whisk in flour, whisking constantly, over low heat 3 minutes. Gradually whisk in milk and bring to a boil. Simmer until flour taste disappears, about 5 minutes. Whisk in cheese until cheese is melted.